| Parameter |
Value |
| Designation |
405P/Lemmon |
| Type |
P |
| Perihelion (tp_cal, UTC) |
2020-12-24T14:12:20.220480Z |
| Orbit solution date (soln_date, UTC) |
2021-05-31T22:43:11Z |
| Obs used |
1017 |
| NEO |
Yes |
| M1 |
18.800 |
| K1 |
4.500 |
| PC |
- |
| Discovery observation (MPC, UTC) |
2020-10-17T03:08:48.076800Z |
| Discovery magnitude (MPC) |
18.80 G |
| Discovery observatory (MPC) |
Z84 · Calar Alto-Schmidt |
Osculating Elements
| Parameter |
Value |
| Epoch (epoch_cal, TDB) |
2017-12-04.0000000 |
| e |
0.68914700 |
| q (au) |
1.121217 |
| a (au) |
3.606904 |
| i (deg) |
9.365069 |
| Ω (om, deg) |
3.311168 |
| ω (w, deg) |
112.292821 |
| M (ma, deg) |
199.344113 |
Magnitude
Scatter + Global Linear
$$
M_a = (19.090 + 2.000\cdot 2.5\log_{10} r) + \epsilon - 2.5\log_{10}\Phi(\theta) + 5\log_{10}\Delta
$$
$$
\theta = 180^\circ - \alpha
$$
$$
\Phi(\theta) = \frac{\delta_{90} D(\theta) + 1}{\delta_{90} + 1},\quad D(\theta) = k\cdot \Phi_{HG}(\theta; g_f) + (1-k)\cdot \Phi_{HG}(\theta; g_b)
$$
$$
\Phi_{HG}(\theta; g) = \left(\frac{1+g^2}{1+g^2-2g\cos\theta}\right)^{3/2},\quad \Phi_{HG}(90^\circ)=1
$$
Model Parameters
| Parameter |
Value |
| H0 |
19.090 |
| n |
2.000 |
| gf |
0.800 |
| gb |
-0.500 |
| k |
0.800 |
| δ90 |
2.314 |
| Parameter |
Symbol |
Range |
Description |
| Absolute magnitude at 1 AU from Sun and Earth |
H0 |
-5 to 20 |
Intrinsic brightness of the comet |
| Photometric slope parameter |
n |
2 to 6 |
Rate of brightness change with heliocentric distance |
| Forward scattering asymmetry factor |
gf |
0.8 to 1 |
Degree of forward scattering |
| Backward scattering asymmetry factor |
gb |
-1 to -0.5 |
Degree of backward scattering |
| Partitioning coefficient |
k |
0.8 to 1 |
Ratio between forward/backward scattering contributions |
| Dust-to-gas brightness ratio |
δ90 |
1 to 10 |
Relative contribution of dust scattering to gas emission |
Reference: EPSC-DPS2025-160
Residuals (Piecewise)
$$\epsilon = a \log_{10} r_{\mathrm{au}} + b$$
| Start (UTC) |
End (UTC) |
a |
b |
| 2020-06-28 |
2020-12-24 |
-1.5360 |
-0.178 |
| 2020-12-24 |
2021-03-05 |
+6.7770 |
-0.321 |
| 2021-03-05 |
2021-05-10 |
-7.1641 |
+1.615 |
log10 r = log10(heliocentric distance / AU), Δ = geocentric distance (AU)
Ephemeris
| Date/Time (UTC) |
RA (J2000) |
Dec (J2000) |
Nearest HIP |
Dist from HIP (arcmin) |
| 2026-03-26 00:00 |
22:19:56.12 |
-15:49:30.1 |
HIP 110176 |
35.10 |
| 2026-03-26 12:00 |
22:20:19.73 |
-15:47:19.6 |
HIP 110454 |
35.83 |
| 2026-03-27 00:00 |
22:20:43.30 |
-15:45:09.4 |
HIP 110454 |
29.96 |
| 2026-03-27 12:00 |
22:21:06.81 |
-15:42:59.6 |
HIP 110454 |
24.20 |
| 2026-03-28 00:00 |
22:21:30.28 |
-15:40:50.0 |
HIP 110454 |
18.64 |
| 2026-03-28 12:00 |
22:21:53.70 |
-15:38:40.7 |
HIP 110454 |
13.52 |
| 2026-03-29 00:00 |
22:22:17.06 |
-15:36:31.7 |
HIP 110454 |
9.55 |
| 2026-03-29 12:00 |
22:22:40.38 |
-15:34:23.0 |
HIP 110454 |
8.50 |
| 2026-03-30 00:00 |
22:23:03.64 |
-15:32:14.6 |
HIP 110454 |
11.19 |
| 2026-03-30 12:00 |
22:23:26.85 |
-15:30:06.6 |
HIP 110514 |
10.51 |
| 2026-03-31 00:00 |
22:23:50.01 |
-15:27:58.8 |
HIP 110514 |
11.50 |
| 2026-03-31 12:00 |
22:24:13.11 |
-15:25:51.4 |
HIP 110514 |
15.00 |
| 2026-04-01 00:00 |
22:24:36.16 |
-15:23:44.3 |
HIP 110701 |
16.56 |
| 2026-04-01 12:00 |
22:24:59.16 |
-15:21:37.6 |
HIP 110701 |
10.86 |
| 2026-04-02 00:00 |
22:25:22.10 |
-15:19:31.1 |
HIP 110701 |
5.66 |
| 2026-04-02 12:00 |
22:25:44.98 |
-15:17:25.0 |
HIP 110701 |
4.02 |
| 2026-04-03 00:00 |
22:26:07.81 |
-15:15:19.3 |
HIP 110701 |
8.35 |
| 2026-04-03 12:00 |
22:26:30.58 |
-15:13:13.9 |
HIP 110701 |
13.87 |
| 2026-04-04 00:00 |
22:26:53.29 |
-15:11:08.8 |
HIP 110723 |
19.07 |
| 2026-04-04 12:00 |
22:27:15.94 |
-15:09:04.1 |
HIP 110723 |
21.92 |
| 2026-04-05 00:00 |
22:27:38.53 |
-15:06:59.8 |
HIP 110723 |
25.80 |
| 2026-04-05 12:00 |
22:28:01.07 |
-15:04:55.9 |
HIP 110723 |
30.30 |
| 2026-04-06 00:00 |
22:28:23.54 |
-15:02:52.3 |
HIP 110723 |
35.17 |
| 2026-04-06 12:00 |
22:28:45.96 |
-15:00:49.1 |
HIP 111086 |
33.87 |
| 2026-04-07 00:00 |
22:29:08.31 |
-14:58:46.3 |
HIP 111086 |
28.93 |
| 2026-04-07 12:00 |
22:29:30.59 |
-14:56:43.8 |
HIP 111086 |
24.37 |
| 2026-04-08 00:00 |
22:29:52.82 |
-14:54:41.8 |
HIP 111086 |
20.44 |
| 2026-04-08 12:00 |
22:30:14.98 |
-14:52:40.2 |
HIP 111086 |
17.54 |
| 2026-04-09 00:00 |
22:30:37.08 |
-14:50:39.0 |
HIP 111086 |
16.23 |
| 2026-04-09 12:00 |
22:30:59.11 |
-14:48:38.2 |
HIP 111141 |
14.62 |
| 2026-04-10 00:00 |
22:31:21.07 |
-14:46:37.8 |
HIP 111141 |
13.79 |
| 2026-04-10 12:00 |
22:31:42.97 |
-14:44:37.8 |
HIP 111141 |
15.19 |
| 2026-04-11 00:00 |
22:32:04.80 |
-14:42:38.3 |
HIP 111141 |
18.31 |
| 2026-04-11 12:00 |
22:32:26.56 |
-14:40:39.2 |
HIP 111141 |
22.42 |
| 2026-04-12 00:00 |
22:32:48.25 |
-14:38:40.5 |
HIP 111141 |
27.07 |
| 2026-04-12 12:00 |
22:33:09.87 |
-14:36:42.3 |
HIP 111141 |
32.01 |
| 2026-04-13 00:00 |
22:33:31.42 |
-14:34:44.5 |
HIP 111424 |
35.01 |
| 2026-04-13 12:00 |
22:33:52.90 |
-14:32:47.2 |
HIP 111424 |
35.27 |
| 2026-04-14 00:00 |
22:34:14.30 |
-14:30:50.4 |
HIP 111424 |
36.37 |
| 2026-04-14 12:00 |
22:34:35.64 |
-14:28:54.1 |
HIP 111646 |
36.25 |
| 2026-04-15 00:00 |
22:34:56.89 |
-14:26:58.2 |
HIP 111646 |
31.90 |
| 2026-04-15 12:00 |
22:35:18.08 |
-14:25:02.8 |
HIP 111646 |
27.97 |
| 2026-04-16 00:00 |
22:35:39.18 |
-14:23:07.9 |
HIP 111646 |
24.64 |